Structures, such as airfoils, propellers, fan blades, helicopter rotor blades, gas turbine engine blades and vanes, engine inlets, and airframe leading edges are subjected to various environmental conditions during use. For instance, the air moving over the structure may include particulate matter, such as sand, or water droplets, such as rain, which impact the structure and cause erosion. Likewise, water or other fluid may wet the surface of the structure and then freeze to form ice. Typically, the structure may include a sheath or coating that protects the structure from such environmental conditions.